The US president hit out at Sadiq Khan in the aftermath of the attack, taking a comment the mayor had made about the increased police presence on London's streets out of context.

A spokesman for the mayor said Mr Khan would not be responding to the comments.

"The mayor is busy working with the police, emergency services and the government to co-ordinate the response to this horrific and cowardly terrorist attack and provide leadership and reassurance to Londoners and visitors to our city,” he said.

"He has more important things to do than respond to Donald Trump's ill-informed tweet that deliberately takes out of context his remarks urging Londoners not to be alarmed when they saw more police - including armed officers - on the streets.”

In a series of tweets posted in the aftermath of the attack Mr Trump appeared to take issue with the mayor's warning that there was "no need to be alarmed” at the increased police presence on the street.

"We must stop being politically correct and get down to the business of security for our people. If we don't get smart it will only get worse,” the President tweeted.

"At least seven dead and 48 wounded in terror attack and Mayor of London says there is 'no reason to be alarmed'!” another of his tweets read.

Mr Khan had said: "Londoners will see increased police presence today and over the course of the next few days. There's no reason to be alarmed.”

The US President also tweeted on the fact the attack did not feature firearms, in a contribution to the US gun debate: "Do you notice we are not having a gun debate right now? That's because they used knives and a truck!”

As news of the attack broke, Mr Trump used the atrocity to promote his travel ban against people from certain Muslim-majority countries.